In accordance with increasing domestic and foreign attention on a 4th-Generation (4G) mobile communication, research is being conducted on systems for meeting the requirements of the 4G mobile communication. Particularly, an Orthogonal Frequency Division Multiplexing (OFDM) scheme, which features high transmission efficiency and a simple channel equalization, attracts attention as one of the suitable schemes for the 4G mobile communication system. The OFDM scheme is adopted as a wireless transmission standard for the Institute of Electrical and Electronics Engineers (IEEE) 802.16 and other systems.
An Orthogonal Frequency Division Multiple Access (OFDMA) scheme, which allocates different subcarriers per the user, transmits data by splitting the frequency band in use into a plurality of small frequency bands (that is, into subchannels and times).
Meanwhile, for the time/frequency resource allocation in the OFDMA based mobile communication system, the resources are allocated using a scheduler, and the allocation information is transmitted using a control signal. To reduce overhead of the control information, the previously allocated region without particular control information can be reused. That is, the resource region of every frame is fixedly allocated and used until the resource region is changed or released separately.
Since a period of using the previously allocated region differs in the fixed allocation, the same resource of a specific time point may be allocated to multiple users at the same time. At this time, the scheduler changes the resource allocation locations of the corresponding users to make them recognize their changed resource allocation regions. When transmitting the changed information, the scheduler needs to send additional control information.
However, conventional methods transmit the additional control information of the changed resource allocation region without taking into account various possible resource collisions in the fixed resource allocation, and thus may suffer the overhead.
Thus, there is a need for an apparatus and a method for efficiently transmitting the control information required to change the fixed resource allocation region in the mobile communication system.